Using the other senses to cut down on accidents

We've got five senses (well, some of us have six, apparently), so why are cars only using maybe one or two to keep us alerted and safe while driving? Dr. Charles Spence, an experimental psychologist at the U of Oxford, thinks using the other senses would be better for keeping drivers' wits about them—apparently vibrating seats, seatbelts, and pedals in conjunction with scents or auditory cues should do the trick. We like the idea of a 10-15% reduction in "most common types of accidents," no doubt, but we just hope driving won't become a horribly irksome experience for it.